1. Field of the Invention
This invention relates to a polyolefin resin composition exhibiting its superior characteristics for high-speed tensile breaking extension while ensuring harmony with a bending elastic modulus.
2. Description of Related Art
Recently, a shock absorbing structure is likely to be employed at various sites from the viewpoint of ensuring human protection. This shock absorbing structure generally comprises a resin based energy absorbing body. Even if a human being bumps against this shock absorbing structure, the resin based energy absorbing body absorbs shock energy at that time. Recently, it is expected to increase capability of absorbing the shock energy of the resin based energy absorbing body (for instance, from the viewpoint of better human protection (reduction of injury or the like), it is expected to enable shock energy to be absorbed over a long time while a crush acceleration at the time of collision is maintained at a low level (in a state in which a speed change is small)).
However, when the shock energy absorbing capability is increased as described above, the thickness of the resin based energy absorbing body muse be thickened, and collision strokes at the time of collision must be increased, thus causing deterioration of the use (mounting) environment of the shock absorbing structure.
The following description will be given with reference to a specific example. The above-mentioned shock absorbing structure is applicable to vehicles such as automobiles having possibility of collision in which a clew (the head or the like) may bump against the body, as disclosed in Japanese Patent Laid-Open Nos. 10-129377 and 10-76893. However, in the case where an attempt is made to lower a maximum acceleration at the time of crush of the resin based energy absorbing body from the viewpoint of better human protection, it becomes impossible to absorb shock energy due to lowered maximum acceleration at the time of the crush. In this case, the thickness of the resin based energy absorbing body must be thickened to ensure the shock absorption stroke. It is difficult to adopt such a construction considering a limited vehicle space.
On the other hand, as disclosed in Japanese Patent Laid-Open No. 8-127298, it is proposed that a resin based energy absorbing body is crushed, and a pillar as a strength member is also deformed by the resin based energy absorbing body to increase shock absorption strokes at the time of collision. Recently, to improve body rigidity, the thickness of the pillar is increased, reinforcement is added, high tension or the like is applied. Therefore, it is difficult to deform the pillar as a strength member to increase the shock absorption strokes based on the above-mentioned proposal.